#define _CRT_SECURE_NO_WARNINGS 1
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
ll cnt, i,day;

int main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	ll a, b, n; cin >> a >> b >> n;
	while (cnt < n) {
		i++;
		if (i == 8) i = 1;
		if (i <= 5) cnt += a;
		else cnt += b;
		day++;
	}
	cout << day << '\n';
	return 0;
}